Select the letter-cluster from among the given options that can replace the question mark (?) in the following series. GBD, JFJ, MJP, PNV ?

Correct — B.
Rule: 1st letter +3, 2nd letter +4, 3rd letter +6, wrapping past Z.

1st: G(7) → J(10) → M(13) → P(16) → S(19)
2nd: B(2) → F(6) → J(10) → N(14) → R(18)
3rd: D(4) → J(10) → P(16) → V(22) → 28 − 26 = B(2)

Next cluster: SRB → option (b).

Why the others are wrong

• (a)
  VHA — V cannot start the next cluster: first letters run G, J, M, P on +3, so S comes next. H and A also miss the +4 and +6 steps, which give R and B.
• (c)
  SRF — F in third place ignores the wrap. V is 22 and 22 + 6 = 28, past Z; subtract 26 to land on 2, which is B, not F.
• (d)
  UHS — U breaks the +3 run of first letters, which gives S after P. The second letter should be R and the third B, so UHS misses in every place.

A letter-cluster series is three separate series running side by side. Number the letters (A = 1 … Z = 26) and follow each position down the terms on its own.

Here the three steps differ, +3, +4 and +6, and the third position runs past Z. When a sum passes 26, subtract 26 to wrap back to the start of the alphabet: V(22) + 6 = 28, and 28 − 26 = 2, which is B.

Key facts

• Anchor positions: E 5, J 10, O 15, T 20, Y 25.
• A sum above 26 wraps by subtracting 26: 28 becomes 2, which is B.
• Each position in a cluster can follow its own step size.

Common traps

• Stopping at V + 6 = 28 and looking for a 28th letter instead of wrapping to B
• Checking only the first two letters, which leaves SRB and SRF tied

No directly related past PYQ was found.